Regular Clogging

[printerfan 5]

After a long series of issues with my UMO, I recently replaced the hotend with a new official hotend pack (new block, peek, ptfe, nozzle, brass barrel, and thermocouple) in hopes that my prints would improve and I would have a more reliable printer.  Well, after installing everything, the printer clogs first attempt with brand new unopened ABS with settings at 250C nozzle, 100C bed, 50 mm/s.  

I attempted clearing the clog by inserting a 0.35 needle through the .4 nozzle opening, but it did not help much.  I removed the nozzle from the block and the nozzle was completely filled with ABS, now discolored from sitting in the hotend for too long.  

I have two questions:

1.  What am I doing wrong that is causing my printer to constantly clog?

    -I have a new official hotend, so that's unlikely the cause.

    -I manually extrude filament before attempting a print by turning the extruder wheel.  

     Could this be causing too much filament to flow into the nozzle and clog it?

2. The nozzle is completely filled with ABS up to the neck (atomic pull NEVER works for me to clear the nozzle, the filament always snaps above the nozzle).  I have read about using a hand torch to burn out the ABS, anyone recommend a particular butane hand torch that gets hot enough to do this?

Edited October 11, 2015 by Guest

[Dim3nsioneer 558]

As I never used a hand torch for cleaning parts I can only give you some remarks on your first question.

As I see, you really exchanged the whole hotend. I assume you made sure that everything is mounted properly. That should exclude a clog higher up in the hotend, e.g. between nozzle and barrel.

Are you using any retraction length larger than 12mm?

Do you use any kind of dust filter for the filament entering the Bowden tube? If not, you may want to try this; I strongly recommend it.

Is the Bowden tube clean and clear? If you see traces of usage on the inside, you may want to replace it. If you want to clean the Bowden tube, you may use a pipe cleaning wire, dry or with some smoke-free oil on it to get a bit of lubrication.

I hope any of these remarks might help you.

[printerfan 5]

I took a look at the block and could see filament in the brass tube... So looks like I will be completely disassembling the hotend. After doing a lot of reading about ABS clogs, I decided to soak the nozzle in acetone, and that looks like what I will be doing with the other parts as well. I will leave them in their for 2 days and see if the clot has dissolved.

I will try to clean my bowden tube and install a filament sponge/duster, but I doubt that is the reason for all of the clogs. From what I have read, dirty filament (in this case I used brand new unopened ABS) and dirty bowden (my bowden probably could use a cleaning) can certainly make your clogging issues worse, but they only contribute to another primary issue causing the clogs.

In terms of my retraction settings in Cura, minimum travel (mm) = 1.5.

What do you think about my practice of manually extruding before a print?

Maybe I could be turning the wheel too fast and it causing filament to over fill the nozzle?

What about preheat settings, when I use the preheat ABS setting on the ulticontroller the nozzle heats up to 250C probably 10 minutes before the bed reachings 100C, maybe this is causing the filament to cook and harden?

[BrayChristopher 36]

Have you checked/replaced the PTFE coupler? That caused me some jams that were hard to diagnose.

[Dim3nsioneer 558]

I took a look at the block and could see filament in the brass tube... So looks like I will be completely disassembling the hotend.  After doing a lot of reading about ABS clogs, I decided to soak the nozzle in acetone, and that looks like what I will be doing with the other parts as well.  I will leave them in their for 2 days and see if the clot has dissolved.  

I will try to clean my bowden tube and install a filament sponge/duster, but I doubt that is the reason for all of the clogs.  From what I have read, dirty filament (in this case I used brand new unopened ABS) and dirty bowden (my bowden probably could use a cleaning) can certainly make your clogging issues worse, but they only contribute to another primary issue causing the clogs.

In terms of my retraction settings in Cura, minimum travel (mm) = 1.5.

What do you think about my practice of manually extruding before a print?  

Maybe I could be turning the wheel too fast and it causing filament to over fill the nozzle?

What about preheat settings, when I use the preheat ABS setting on the ulticontroller the nozzle heats up to 250C probably 10 minutes before the bed reachings 100C, maybe this is causing the filament to cook and harden?

 

The 12mm were related to retraction distance, not minimum travel distance... most probably something between 3.5 and 5 mm...

Manual extrusion before a print is fine, I also do this, but quite slowly... just get a steady flow out of the nozzle....

I'm not an ABS expert. That means I cannot comment on effects due to standing and heated ABS filament. But if you can avoid it I would...

[tommyph1208 55]

I took a look at the block and could see filament in the brass tube... So looks like I will be completely disassembling the hotend.  After doing a lot of reading about ABS clogs, I decided to soak the nozzle in acetone, and that looks like what I will be doing with the other parts as well.  I will leave them in their for 2 days and see if the clot has dissolved.  

I will try to clean my bowden tube and install a filament sponge/duster, but I doubt that is the reason for all of the clogs.  From what I have read, dirty filament (in this case I used brand new unopened ABS) and dirty bowden (my bowden probably could use a cleaning) can certainly make your clogging issues worse, but they only contribute to another primary issue causing the clogs.

In terms of my retraction settings in Cura, minimum travel (mm) = 1.5.

What do you think about my practice of manually extruding before a print?  

Maybe I could be turning the wheel too fast and it causing filament to over fill the nozzle?

What about preheat settings, when I use the preheat ABS setting on the ulticontroller the nozzle heats up to 250C probably 10 minutes before the bed reachings 100C, maybe this is causing the filament to cook and harden?

 

My experience with ABS is also limited to what I have accumulated through reading over the years, so can't help a lot with that specifically... I noted however, that you say that your preheat ABS option will first heat your nozzle, then spend 10 minutes heating the bed...? Is this the same if you just hit "print" without preheat?

My preheat options all heat the bed first, then the nozzle, and I think this is the right way to go... As you yourself note, having filament sitting at temp for 10 minutes in the nozzle, is not a good thing, its very likely that it will get burned and maybe harden up... I would look into how you can change the heating order... Probably you can for a print, edit it directly in the G-code by just switching a few lines. with the preheat options, I'm not sure, but it must be configurable in firmware.

If you cant find it, I know that there is also some features in marlin for extruding a bit of filament every x seconds when the hotend is at temp and the printer is idle... this is exactly there to prevent filament getting burned in the nozzle.

[gr5 2,224]

What about preheat settings, when I use the preheat ABS setting on the ulticontroller the nozzle heats up to 250C probably 10 minutes before the bed reachings 100C, maybe this is causing the filament to cook and harden?

 

Wow! That's the problem right there! Do not leave the ABS at 250C for so long. It will turn into this gunk that is like gum left under a table for a year in a restaurant.

Did you soak the peek part in acetone? Someone else asked if that is okay to do. I didn't know the answer.

[macua85 52]

I had this problem also when i changed my hotend parts for OEM, here is my post on how I sorted it:

Right, I figured out the jamming problem, and its pretty disappointing. When I built up my hot ends originally, I used cheap Chinese parts. They worked perfectly fine, no problems or wearing out. However, I thought it would be best to replace them all with OEM ultimaker parts for longevity. This is when the problems occurred. After a few hours of frustration and testing/investigation, I found that on a large retraction, filament was forming a ring between the Teflon isolator and the brass heat break in the PEEK. Now, this gap shouldn't have been there. The peek had been incorrectly machined leaving a lip above the threads so the Teflon isolator couldn't sit all the way down, and make contact with the brass piece. I gently dremeled it out, and now have no jamming. Wasted 3 nights this week on that problem!